A frequency counter is an electronic test instrument that counts pulses in an electronic signal to determine frequency. Traditional frequency counters have multiple hardware circuits for analyzing a broad range of input signals of varying frequencies. For example, frequency counter hardware is capable of analyzing and displaying low frequency signals with little pre-conditioning. Accordingly, a low frequency input port can receive and display low frequency signals without needing preconditioning circuits. A high frequency input port can receive and display higher frequency input signals by routing an input signal through preconditioning circuits to reduce the frequency of the signal to a frequency range the hardware is capable of measuring.
But there are shortcomings with the conventional systems. For example, a traditional frequency counter requires the user to manually transfer the input signal between the ports when the frequency drops into the lower band from the higher band or vice versa. Such a manual transfer is impractical for high speed complex signals that rapidly change frequencies. Further, the traditional frequency counter employs a single conditioning circuit locked to a maximum conditioning value to accommodate the highest frequency signal allowed for the device. As a result, input signals on the low frequency end of the high frequency band are over adjusted resulting in increased jitter. Further, the conditioning circuits are typically high frequency coupled and are not amenable to trigger level based conditioning.
Embodiments of the invention address these and other issues in the prior art.